1. Field of the Invention
The present invention relates to a theft deterrent system for a vehicle with a vehicular electronic key system applied thereto which permits, for example, starting of an engine of the vehicle when an on-board device judges that this request for starting the engine is a request from a regular user-carried portable electronic key as a result of radio intercommunication between the portable electronic key and the on-board device and subsequent collation of an identification code (ID). Particularly, the present invention is concerned with a theft deterrent system for a vehicle suitable for application to a motorcycle or the like, on which is mounted a warning device for the prevention of theft.
2. Description of the Background Art
In a conventional vehicular electronic key system, a starting switch is attached to a four-wheeled vehicle whereby the vehicle is turned on. Specifically, the starting switch may be attached to, for example, a door handlebar or a trunk lid. When a user operates the starting switch, communication with the portable electronic key begins, then collation is made between ID transmitted from the portable electronic key and an ID registered in the on-board device and, for example, locked doors are unlocked upon coincidence of both IDs. This type of system is disclosed, for example, in JP-A No. 349117/2001.
In JP-A No. 349117/2001, it is disclosed that the starting switch is also attached to an ignition knob. When the user operates the ignition knob after getting on the four-wheeled vehicle, the on-board device again communicates with the portable electronic key, followed by collation of IDs for approval of starting the engine. Then, upon coincidence of IDs, the engine starts.
Thus, in the conventional vehicular electronic key system for a four-wheeled vehicle, the presence of a regular portable electronic key is an essential condition for unlocking doors and for starting the engine.
There has been proposed a vehicular electronic key system for use in a motorcycle in which random numbers are generated on the basis of the starting time data taken after turning ON a power supply of an immobilizer until start of an engine, then information peculiar to the key is encrypted on the basis of the random numbers to generate an authentication key and an authentication code. Authentication is performed using the authentication key and the authentication code, whereby the prevention of theft can be positively effected. This type of vehicular electronic key system is disclosed, for example, in JP-A No. 12123/2001.
An excellent vehicular electronic key system has been proposed for a motorcycle or the like in which a warning lamp is turned ON in the event that a user happens to drop a portable electronic key during a vehicle stop or when the vehicle is in motion, thereby diminishing the probability of loss of the portable electronic key. This type of vehicular electronic key system is disclosed, for example, in JP-A No. 114860/2004.
Further, a vehicular electronic key system for a motorcycle has been proposed including a system with a theft deterrent system installed therein. This type of vehicular electronic key system is disclosed, for example, in JP-A No. 114835/2004.
In the theft deterrent system described in JP-A No. 114835/2004, a vibration sensor is attached to the vehicle. When the proper authentication procedure is not made between an on-board device and a portable electronic key, for example when a main switch is in a locked state, and when it is detected by the vibration sensor that the vehicle body was vibrated to a greater extent than a predetermined level, then a buzzer is operated to output a warning sound, thereby preventing the occurrence of theft.
However, in the vehicle with the above-described theft deterrent system mounted thereon, vibration is detected by the vibration sensor at other times when operations are performed with the main switch in the locking position. For example, during fuel supply, which may be performed with the main switch in a locked state, if the value of the detected vibration is not smaller than a predetermined value, a warning sound issues from the buzzer.
The present invention has been accomplished in connection with such a technique, and it is an object of the invention, to provide a theft deterrent system for a vehicle which permits a warning device to be positively switched to a non-operable state when a user, who carries a regular portable electronic key, does not want operation of the warning device.
It is another object of the present invention to provide a theft deterrent system for a vehicle which permits a warning device to be positively switched to an operation stand-by state when a user, who carries a regular portable electronic key, wants to bring the warning device into the operation stand-by state.